Semiconductor devices have a plurality of bump electrodes, which are formed on one side of a semiconductor substrate. Some of these devices have a chip size package structure, i.e., CSP structure. The CSP structure provides that a size of a chip is almost equal to a size of a package. The semiconductor device with CSP structure can be used as a power electronic device, so that comparably heavy current flows in an electric circuit of the power electronic device.
As shown in FIG. 5, a semiconductor device 20 with CSP structure according to a related art includes a plurality of bump electrodes 6a, which is disposed on the upper surface 20a of a semiconductor substrate 1. As shown in FIG. 6, the bump electrodes 6a are formed on a predetermined area of the upper surface 20a. This predetermined area is surrounded with a support area 8.
The support area 8 is needed for supporting the semiconductor device 20. In general, the semiconductor device 20 is carried by a tray 10, which is a container having a plate-like shape, as shown in FIG. 7. The tray 10 with a cap 11 supports both sides of the semiconductor device 20. The cap 11 supports the lower surface 20b of the semiconductor device 20, which is opposite to the upper surface 20a of the semiconductor device 20, so that all of the lower surface 20b is covered with the cap 11. On the upper surface 20a, the semiconductor device 20 is supported with the tray 10, so that the support area 8 of the upper surface 20a is covered with the tray 10. Therefore, the support area 8 is needed for carrying the semiconductor device 20.
In recent years, more and more bump electrodes 6a are required as external connection terminals, because of a high-density integration and a multipurpose electric circuit. Therefore, a wide area for forming the bump electrode 6a is needed. However, no bump electrode 6a can be formed on the support area 8, which is disposed on the peripheral surface of the upper surface 20a so as to support the semiconductor device 20. Thus, it is difficult to increase the bump electrode 6a. 